Whatsapp solved a problem which was how to communicate via instant message without incurring the costs of SMS. Square doesn't solve a problem unless you consider providing payment services to unprofitable merchants one. Perhaps Square can move upstream to larger businesses and organizations but now they are moving into a heavily saturated market with no clear competitive advantage. Square is failing in Canada and the UK due to the lack of EMV and pin debit support and that will eventually become their fate in the US as well.